Engaging a delegate for modification of an index structure

ABSTRACT

A method includes identifying, by a computing device of a dispersed storage network (DSN), a delegate device of a plurality of delegate devices of the DSN for processing a change to a node of a plurality of nodes of a hierarchical index structure. The method further includes sending, by the computing device, a change type specific request to the delegate device regarding the change to the node. The method further includes determining, by the delegate device, whether the delegate device is responsible for executing the change type specific request. When the delegate device is responsible for executing the change type specific request, the method further includes sending, by the delegate device, a response message to the computing device indicating that the delegate device is responsible for executing the change type specific request. The method further includes executing, by the delegate device, the change type specific request.

CROSS-REFERENCE TO RELATED APPLICATIONS

The present U.S. Utility Patent Application claims priority pursuant to35 U.S.C. § 119(e) to U.S. Provisional Application No. 62/248,636,entitled “SECURELY STORING DATA IN A DISPERSED STORAGE NETWORK”, filedOct. 30, 2015, which is hereby incorporated herein by reference in itsentirety and made part of the present U.S. Utility Patent Applicationfor all purposes.

STATEMENT REGARDING FEDERALLY SPONSORED RESEARCH OR DEVELOPMENT

Not applicable.

INCORPORATION-BY-REFERENCE OF MATERIAL SUBMITTED ON A COMPACT DISC

Not applicable.

BACKGROUND OF THE INVENTION Technical Field of the Invention

This invention relates generally to computer networks and moreparticularly to dispersing error encoded data.

Description of Related Art

Computing devices are known to communicate data, process data, and/orstore data. Such computing devices range from wireless smart phones,laptops, tablets, personal computers (PC), work stations, and video gamedevices, to data centers that support millions of web searches, stocktrades, or on-line purchases every day. In general, a computing deviceincludes a central processing unit (CPU), a memory system, userinput/output interfaces, peripheral device interfaces, and aninterconnecting bus structure.

As is further known, a computer may effectively extend its CPU by using“cloud computing” to perform one or more computing functions (e.g., aservice, an application, an algorithm, an arithmetic logic function,etc.) on behalf of the computer. Further, for large services,applications, and/or functions, cloud computing may be performed bymultiple cloud computing resources in a distributed manner to improvethe response time for completion of the service, application, and/orfunction. For example, Hadoop is an open source software framework thatsupports distributed applications enabling application execution bythousands of computers.

In addition to cloud computing, a computer may use “cloud storage” aspart of its memory system. As is known, cloud storage enables a user,via its computer, to store files, applications, etc. on an Internetstorage system. The Internet storage system may include a RAID(redundant array of independent disks) system and/or a dispersed storagesystem that uses an error correction scheme to encode data for storage.

In cloud storage systems, it is common to use one or more indexstructures to improve the ease of finding data. For example, one indexstructure is used for find data based on alphabetic indexing. As anotherexample, another index structure is used to find data based on key wordscontained in the title of the data. As yet another example, anotherindex structure is used to find data based on the type of data (e.g.,video, audio, text, pictures, etc.). As the data changes within thecloud storage system, one or more index structures may need to beupdated.

BRIEF DESCRIPTION OF THE SEVERAL VIEWS OF THE DRAWING(S)

FIG. 1 is a schematic block diagram of an embodiment of a dispersed ordistributed storage network (DSN) in accordance with the presentinvention;

FIG. 2 is a schematic block diagram of an embodiment of a computing corein accordance with the present invention;

FIG. 3 is a schematic block diagram of an example of dispersed storageerror encoding of data in accordance with the present invention;

FIG. 4 is a schematic block diagram of a generic example of an errorencoding function in accordance with the present invention;

FIG. 5 is a schematic block diagram of a specific example of an errorencoding function in accordance with the present invention;

FIG. 6 is a schematic block diagram of an example of a slice name of anencoded data slice (EDS) in accordance with the present invention;

FIG. 7 is a schematic block diagram of an example of dispersed storageerror decoding of data in accordance with the present invention;

FIG. 8 is a schematic block diagram of a generic example of an errordecoding function in accordance with the present invention;

FIG. 9 is a schematic block diagram of an embodiment of a hierarchicalindex structure in accordance with the present invention;

FIG. 10 is a schematic block diagram of an example of an index node inaccordance with the present invention;

FIG. 11 is a schematic block diagram of an example of a leaf node inaccordance with the present invention;

FIG. 12 is a schematic block diagram of an embodiment of engaging adelegate for updating a hierarchical index structure of a DSN inaccordance with the present invention;

FIG. 13 is a logic diagram of an example of a method of engaging adelegate for a hierarchical index structure of a DSN in accordance withthe present invention;

FIG. 14 is a logic diagram of another example of a method of engaging adelegate for a hierarchical index structure of a DSN in accordance withthe present invention; and

FIG. 15 is a logic diagram of another example of a method of engaging adelegate for a hierarchical index structure of a DSN in accordance withthe present invention.

DETAILED DESCRIPTION OF THE INVENTION

FIG. 1 is a schematic block diagram of an embodiment of a dispersed, ordistributed, storage network (DSN) 10 that includes a plurality ofcomputing devices 12-16, a managing unit 18, an integrity processingunit 20, and a DSN memory 22. The components of the DSN 10 are coupledto a network 24, which may include one or more wireless and/or wirelined communication systems; one or more non-public intranet systemsand/or public internet systems; and/or one or more local area networks(LAN) and/or wide area networks (WAN).

The DSN memory 22 includes a plurality of storage units 36 that may belocated at geographically different sites (e.g., one in Chicago, one inMilwaukee, etc.), at a common site, or a combination thereof. Forexample, if the DSN memory 22 includes eight storage units 36, eachstorage unit is located at a different site. As another example, if theDSN memory 22 includes eight storage units 36, all eight storage unitsare located at the same site. As yet another example, if the DSN memory22 includes eight storage units 36, a first pair of storage units are ata first common site, a second pair of storage units are at a secondcommon site, a third pair of storage units are at a third common site,and a fourth pair of storage units are at a fourth common site. Notethat a DSN memory 22 may include more or less than eight storage units36. Further note that each storage unit 36 includes a computing core (asshown in FIG. 2, or components thereof) and a plurality of memorydevices for storing dispersed error encoded data.

Each of the computing devices 12-16, the managing unit 18, and theintegrity processing unit 20 include a computing core 26, which includesnetwork interfaces 30-33. Computing devices 12-16 may each be a portablecomputing device and/or a fixed computing device. A portable computingdevice may be a social networking device, a gaming device, a cell phone,a smart phone, a digital assistant, a digital music player, a digitalvideo player, a laptop computer, a handheld computer, a tablet, a videogame controller, and/or any other portable device that includes acomputing core. A fixed computing device may be a computer (PC), acomputer server, a cable set-top box, a satellite receiver, a televisionset, a printer, a fax machine, home entertainment equipment, a videogame console, and/or any type of home or office computing equipment.Note that each of the managing unit 18 and the integrity processing unit20 may be separate computing devices, may be a common computing device,and/or may be integrated into one or more of the computing devices 12-16and/or into one or more of the storage units 36.

Each interface 30, 32, and 33 includes software and hardware to supportone or more communication links via the network 24 indirectly and/ordirectly. For example, interface 30 supports a communication link (e.g.,wired, wireless, direct, via a LAN, via the network 24, etc.) betweencomputing devices 14 and 16. As another example, interface 32 supportscommunication links (e.g., a wired connection, a wireless connection, aLAN connection, and/or any other type of connection to/from the network24) between computing devices 12 and 16 and the DSN memory 22. As yetanother example, interface 33 supports a communication link for each ofthe managing unit 18 and the integrity processing unit 20 to the network24.

Computing devices 12 and 16 include a dispersed storage (DS) clientmodule 34, which enables the computing device to dispersed storage errorencode and decode data (e.g., data 40) as subsequently described withreference to one or more of FIGS. 3-8. In this example embodiment,computing device 16 functions as a dispersed storage processing agentfor computing device 14. In this role, computing device 16 dispersedstorage error encodes and decodes data on behalf of computing device 14.With the use of dispersed storage error encoding and decoding, the DSN10 is tolerant of a significant number of storage unit failures (thenumber of failures is based on parameters of the dispersed storage errorencoding function) without loss of data and without the need for aredundant or backup copies of the data. Further, the DSN 10 stores datafor an indefinite period of time without data loss and in a securemanner (e.g., the system is very resistant to unauthorized attempts ataccessing the data).

In operation, the managing unit 18 performs DS management services. Forexample, the managing unit 18 establishes distributed data storageparameters (e.g., vault creation, distributed storage parameters,security parameters, billing information, user profile information,etc.) for computing devices 12-14 individually or as part of a group ofuser devices. As a specific example, the managing unit 18 coordinatescreation of a vault (e.g., a virtual memory block associated with aportion of an overall namespace of the DSN) within the DSN memory 22 fora user device, a group of devices, or for public access and establishesper vault dispersed storage (DS) error encoding parameters for a vault.The managing unit 18 facilitates storage of DS error encoding parametersfor each vault by updating registry information of the DSN 10, where theregistry information may be stored in the DSN memory 22, a computingdevice 12-16, the managing unit 18, and/or the integrity processing unit20.

The managing unit 18 creates and stores user profile information (e.g.,an access control list (ACL)) in local memory and/or within memory ofthe DSN memory 22. The user profile information includes authenticationinformation, permissions, and/or the security parameters. The securityparameters may include encryption/decryption scheme, one or moreencryption keys, key generation scheme, and/or data encoding/decodingscheme.

The managing unit 18 creates billing information for a particular user,a user group, a vault access, public vault access, etc. For instance,the managing unit 18 tracks the number of times a user accesses anon-public vault and/or public vaults, which can be used to generate aper-access billing information. In another instance, the managing unit18 tracks the amount of data stored and/or retrieved by a user deviceand/or a user group, which can be used to generate a per-data-amountbilling information.

As another example, the managing unit 18 performs network operations,network administration, and/or network maintenance. Network operationsincludes authenticating user data allocation requests (e.g., read and/orwrite requests), managing creation of vaults, establishingauthentication credentials for user devices, adding/deleting components(e.g., user devices, storage units, and/or computing devices with a DSclient module 34) to/from the DSN 10, and/or establishing authenticationcredentials for the storage units 36. Network administration includesmonitoring devices and/or units for failures, maintaining vaultinformation, determining device and/or unit activation status,determining device and/or unit loading, and/or determining any othersystem level operation that affects the performance level of the DSN 10.Network maintenance includes facilitating replacing, upgrading,repairing, and/or expanding a device and/or unit of the DSN 10.

The integrity processing unit 20 performs rebuilding of ‘bad’ or missingencoded data slices. At a high level, the integrity processing unit 20performs rebuilding by periodically attempting to retrieve/list encodeddata slices, and/or slice names of the encoded data slices, from the DSNmemory 22. For retrieved encoded slices, they are checked for errors dueto data corruption, outdated version, etc. If a slice includes an error,it is flagged as a ‘bad’ slice. For encoded data slices that were notreceived and/or not listed, they are flagged as missing slices. Badand/or missing slices are subsequently rebuilt using other retrievedencoded data slices that are deemed to be good slices to produce rebuiltslices. The rebuilt slices are stored in the DSN memory 22.

FIG. 2 is a schematic block diagram of an embodiment of a computing core26 that includes a processing module 50, a memory controller 52, mainmemory 54, a video graphics processing unit 55, an input/output (IO)controller 56, a peripheral component interconnect (PCI) interface 58,an IO interface module 60, at least one IO device interface module 62, aread only memory (ROM) basic input output system (BIOS) 64, and one ormore memory interface modules. The one or more memory interfacemodule(s) includes one or more of a universal serial bus (USB) interfacemodule 66, a host bus adapter (HBA) interface module 68, a networkinterface module 70, a flash interface module 72, a hard drive interfacemodule 74, and a DSN interface module 76.

The DSN interface module 76 functions to mimic a conventional operatingsystem (OS) file system interface (e.g., network file system (NFS),flash file system (FFS), disk file system (DFS), file transfer protocol(FTP), web-based distributed authoring and versioning (WebDAV), etc.)and/or a block memory interface (e.g., small computer system interface(SCSI), internet small computer system interface (iSCSI), etc.). The DSNinterface module 76 and/or the network interface module 70 may functionas one or more of the interface 30-33 of FIG. 1. Note that the IO deviceinterface module 62 and/or the memory interface modules 66-76 may becollectively or individually referred to as IO ports.

FIG. 3 is a schematic block diagram of an example of dispersed storageerror encoding of data. When a computing device 12 or 16 has data tostore it disperse storage error encodes the data in accordance with adispersed storage error encoding process based on dispersed storageerror encoding parameters. The dispersed storage error encodingparameters include an encoding function (e.g., information dispersalalgorithm, Reed-Solomon, Cauchy Reed-Solomon, systematic encoding,non-systematic encoding, on-line codes, etc.), a data segmentingprotocol (e.g., data segment size, fixed, variable, etc.), and per datasegment encoding values. The per data segment encoding values include atotal, or pillar width, number (T) of encoded data slices per encodingof a data segment (i.e., in a set of encoded data slices); a decodethreshold number (D) of encoded data slices of a set of encoded dataslices that are needed to recover the data segment; a read thresholdnumber (R) of encoded data slices to indicate a number of encoded dataslices per set to be read from storage for decoding of the data segment;and/or a write threshold number (W) to indicate a number of encoded dataslices per set that must be accurately stored before the encoded datasegment is deemed to have been properly stored. The dispersed storageerror encoding parameters may further include slicing information (e.g.,the number of encoded data slices that will be created for each datasegment) and/or slice security information (e.g., per encoded data sliceencryption, compression, integrity checksum, etc.).

In the present example, Cauchy Reed-Solomon has been selected as theencoding function (a generic example is shown in FIG. 4 and a specificexample is shown in FIG. 5); the data segmenting protocol is to dividethe data object into fixed sized data segments; and the per data segmentencoding values include: a pillar width of 5, a decode threshold of 3, aread threshold of 4, and a write threshold of 4. In accordance with thedata segmenting protocol, the computing device 12 or 16 divides the data(e.g., a file (e.g., text, video, audio, etc.), a data object, or otherdata arrangement) into a plurality of fixed sized data segments (e.g., 1through Y of a fixed size in range of Kilo-bytes to Tera-bytes or more).The number of data segments created is dependent of the size of the dataand the data segmenting protocol.

The computing device 12 or 16 then disperse storage error encodes a datasegment using the selected encoding function (e.g., Cauchy Reed-Solomon)to produce a set of encoded data slices. FIG. 4 illustrates a genericCauchy Reed-Solomon encoding function, which includes an encoding matrix(EM), a data matrix (DM), and a coded matrix (CM). The size of theencoding matrix (EM) is dependent on the pillar width number (T) and thedecode threshold number (D) of selected per data segment encodingvalues. To produce the data matrix (DM), the data segment is dividedinto a plurality of data blocks and the data blocks are arranged into Dnumber of rows with Z data blocks per row. Note that Z is a function ofthe number of data blocks created from the data segment and the decodethreshold number (D). The coded matrix is produced by matrix multiplyingthe data matrix by the encoding matrix.

FIG. 5 illustrates a specific example of Cauchy Reed-Solomon encodingwith a pillar number (T) of five and decode threshold number of three.In this example, a first data segment is divided into twelve data blocks(D1-D12). The coded matrix includes five rows of coded data blocks,where the first row of X11-X14 corresponds to a first encoded data slice(EDS 1_1), the second row of X21-X24 corresponds to a second encodeddata slice (EDS 2_1), the third row of X31-X34 corresponds to a thirdencoded data slice (EDS 3_1), the fourth row of X41-X44 corresponds to afourth encoded data slice (EDS 4_1), and the fifth row of X51-X54corresponds to a fifth encoded data slice (EDS 5_1). Note that thesecond number of the EDS designation corresponds to the data segmentnumber.

Returning to the discussion of FIG. 3, the computing device also createsa slice name (SN) for each encoded data slice (EDS) in the set ofencoded data slices. A typical format for a slice name 80 is shown inFIG. 6. As shown, the slice name (SN) 80 includes a pillar number of theencoded data slice (e.g., one of 1-T), a data segment number (e.g., oneof 1-Y), a vault identifier (ID), a data object identifier (ID), and mayfurther include revision level information of the encoded data slices.The slice name functions as, at least part of, a DSN address for theencoded data slice for storage and retrieval from the DSN memory 22.

As a result of encoding, the computing device 12 or 16 produces aplurality of sets of encoded data slices, which are provided with theirrespective slice names to the storage units for storage. As shown, thefirst set of encoded data slices includes EDS 1_1 through EDS 5_1 andthe first set of slice names includes SN 1_1 through SN 5_1 and the lastset of encoded data slices includes EDS 1_Y through EDS 5_Y and the lastset of slice names includes SN 1_Y through SN 5_Y.

FIG. 7 is a schematic block diagram of an example of dispersed storageerror decoding of a data object that was dispersed storage error encodedand stored in the example of FIG. 4. In this example, the computingdevice 12 or 16 retrieves from the storage units at least the decodethreshold number of encoded data slices per data segment. As a specificexample, the computing device retrieves a read threshold number ofencoded data slices.

To recover a data segment from a decode threshold number of encoded dataslices, the computing device uses a decoding function as shown in FIG.8. As shown, the decoding function is essentially an inverse of theencoding function of FIG. 4. The coded matrix includes a decodethreshold number of rows (e.g., three in this example) and the decodingmatrix in an inversion of the encoding matrix that includes thecorresponding rows of the coded matrix. For example, if the coded matrixincludes rows 1, 2, and 4, the encoding matrix is reduced to rows 1, 2,and 4, and then inverted to produce the decoding matrix.

FIG. 9 is a diagram illustrating an example of a distributed indexstructure 350 of one or more indexes utilized to access a data object ofone or more data objects 1_1 through 1_w, 3_1 through 3_w, 4_1 through4_w, etc., where at least some of the one or more data objects arestored in at least one of a distributed storage and task network (DSTN)and a dispersed storage network (DSN), and where a data object of theone or more data objects is dispersed storage error encoded to produce aplurality sets of encoded data slices, and where the plurality of setsof encoded data slices are stored in the DSN (e.g., and/or DSTN)utilizing a common source name (e.g., DSN address). The source nameprovides a DSTN and/or DSN address including one or more of vaultidentifier (ID) (e.g., such a vault ID associates a portion of storageresources of the DSN with one or more DSN user devices), a vaultgeneration indicator (e.g., identify a vault generation of one or moreof generations), and an object number that corresponds to the dataobject (e.g., a random number assigned to the data object when the dataobject is stored in the DSN).

The distributed index structure 350 includes at least two nodesrepresented in the index structure as nodes associated with two or morenode levels. One or more nodes of the at least two nodes of thedistributed index structure 350 may be dispersed storage error encodedto produce one or more sets of encoded index slices. The one or moresets of encoded index slices may be stored in at least one of a localmemory, a DSN memory, and a distributed storage and task network (DSTN)module. For example, each node of a 100 node distributed index structureare individually dispersed storage error encoded to produce at least 100sets of encoded index slices for storage in the DSTN module. As anotherexample, the 100 node index structure is aggregated into one index fileand the index file is dispersed storage error encoded to produce a setof encoded index slices for storage in the DSTN module.

Each node of the at least two nodes includes at least one of an indexnode and a leaf node. One index node of the at least two nodes includesa root index node. Alternatively, the distributed index structure 350includes just one node, wherein the one node is a leaf node and wherethe leaf node is a root node. The distributed index structure 350 mayinclude any number of index nodes, any number of leaf nodes, and anynumber of node levels. Each level of the any number of node levelsincludes nodes of a common node type. For example, all nodes of nodelevel 4 are leaf nodes and all nodes of node level 3 are index nodes. Asanother example, as illustrated, the distributed index structure 350includes eight index nodes and eight leaf nodes, where the eight indexnodes are organized in three node levels, where a first node levelincludes a root index node 1_1, a second node level includes index nodes2_1, 2_2, and 2_3, and a third node level includes index nodes 3_1, 3_2,3_3, 3_4, and 3_5, and where the eight leaf nodes are organized in alast (e.g., fourth) node level, where the last node level includes leafnodes 4_1, 4_2, 4_3, 4_4, 4_5, 4_6, 4_7, and 4_8.

Each data object of the one more data objects is associated with atleast one index key per distributed index structure of the one or moredistributed indexes, where the index key includes a searchable elementof the distributed index and may be utilized to locate the data objectin accordance with key type traits. An index key type of an index keyincludes a category of the index key (e.g. string integer, etc.). Anindex key type exhibits traits. Each index key is associated with one ormore key type traits (e.g., for an associated index structure), where akey type traits includes one or more of a type indicator, a traitindicator, a comparing function (e.g., defining how an associate indexkey of this type should be compared, such as sorting and/ormanipulation, to other such index keys), a serialization function (e.g.,encoding function for storage), a de-serialization function (e.g.,decoding function for retrieval), and an absolute minimum value of theindex key.

Each leaf node of the at least two nodes may be associated with one ormore data objects. The association includes at least one of, for eachdata object of the one more data objects, storing an index keyassociated with the data object in the leaf node, storing a source nameassociated with the data object in the leaf node, and storing the dataobject in the leaf node. For example, leaf node 4_2 includes a dataobject 4_2 and an index key associated with data object 4_2. As anotherexample, leaf node 4_3 includes source names associated with data object3_1 through 3_w and index keys associated with data object 3_1 through3_w. Each leaf node is associated with a minimum index key, where theminimum index key is a minimum value of one or more index keysassociated with the one or more data objects in accordance with the keytype traits (e.g., sorted utilizing a comparing function of the key typetraits to identify the minimum value).

Each leaf node is a child in a parent-child relationship with one indexnode, where the one index node is a parent in the parent-childrelationship. Each child node has one parent node and each parent nodehas one or more child nodes. The one index node (e.g., parent node)stores a minimum index key associated with the leaf node (e.g., childnode). As such, a parent node stores a minimum index key for each childnode of the one or more child nodes. Two index nodes may form aparent-child relationship. In such a parent-child relationship, aparent-child node pair is represented in the index structure with aparent node of the parent-child relationship associated with a parentnode level that is one level above in the index structure than a childnode level associated with a child node of the parent-childrelationship.

A leaf node is a sibling node of another leaf node when a minimum indexkey associated with the leaf node is ordered greater than a last minimumindex key associated with the other leaf node, where the last minimumindex key associated with the leaf node is sorted above any other lastminimum index keys associated with any other lower order leaf nodes andwhere the minimum index key associated with the leaf node is orderedless than any other minimum index keys associated with any other higherorder leaf nodes. A sibling node of a node is represented in the indexstructure on a common level with the node and one node position to theright. A last node on the far right of a node level has a no sibling(e.g., null sibling). All other nodes, if any, other than a last farright node, of a common node level have a sibling node. For example,leaf node 4_2 is a sibling node to leaf node 4_1, leaf node 4_3 is asibling node to leaf node 4_2, etc., leaf node 4_8 is a sibling node toleaf node 4_7 and leaf node 4_8 has no sibling node.

Each index node of the at least two nodes may be associated with one ormore child nodes. Such a child node includes at least one of anotherindex node or a leaf node. The association includes, for each child nodeof the one more child nodes, storing a minimum index key associated withthe child node in the index node and storing a source name associatedwith the child node in the index node. Each child node is associatedwith a minimum index key, where the minimum index key is a minimum valueof one or more index keys associated with the child node (e.g., theminimum index key is a minimum value of one or more index keysassociated with one or more children nodes of the child node or one ormore data objects of the child node in accordance with the key typetraits, sorted utilizing a comparing function of the key type traits toidentify the minimum value when the child node is a leaf node). Forexample, index node 3_2 includes a minimum index key (e.g., of dataobject 3_1) and source name associated with leaf node 4_3. As anotherexample, index node 3_3 includes a minimum index key and source nameassociated with leaf node 4_4 and another minimum index key and anothersource name associated with leaf node 4_5. As yet another example, indexnode 2_3 includes a minimum index key and source name associated withindex node 3_4 and minimum index key and another source name associatedwith index node 3_5.

An index node is a sibling node of another index node when a minimumindex key associated with the index node is ordered greater than a lastminimum index key associated with the other index node, where the lastminimum index key associated with the index node is sorted above anyother last minimum index keys associated with any other lower orderindex nodes and where the minimum index key associated with the indexnode is ordered less than any other minimum index keys associated withany other higher order index nodes. For example, index node 3_2 is asibling node to index node 3_1, index node 3_3 is a sibling node toindex node 3_2, etc., index node 3_6 is a sibling node to index node 3_5and index node 3_6 has no sibling node.

FIG. 10 is a diagram illustrating an example of an index node structure352 for an index node that includes index node information 356, siblingnode information 358, and children node information 360. Alternatively,there is no sibling node information 358 when the index node has nosibling node. The index node information 356 includes one or more of anindex node source name field 362, an index node revision field 364, anda node type field 366. Inclusion and/or use of the index node sourcename field 362 and the index node revision field 364 is optional.

The sibling node information 358 includes a sibling node source namefield 368, a sibling minimum index key field 370, and a sibling key typetraits field 372. Inclusion and/or use of the sibling key type traitsfield 372 is optional. The children node information 360 includes one ormore child node information sections 374, 376, etc. corresponding toeach child node of the index node. Each child node information sectionof the one or more child node information sections includes acorresponding child node source name field 378, a corresponding childminimum index key field 380, and a corresponding child key type traitsfield 382. For example, the corresponding child node source name field378 of a child 1 node information section 374 includes a child 1 nodesource name entry. Inclusion and/or use of the corresponding child keytype traits field 382 is optional.

The index node source name field 362 may include an index node dispersedstorage network (DSN) address 354 entry (e.g., source name)corresponding to a storage location for the index node. The index noderevision field 364 may include an index node revision entrycorresponding to a revision number of information contained in the indexnode. Use of the index node revision field 364 enables generating two ormore similar indexes while saving each revision of the two or moresimilar indexes. The node type field 366 includes a node type entry,where the node type entry indicates whether the node is a leaf node ornot a leaf node. The node type indicates that the node is not a leafnode when the node is the index node.

The sibling node source name field 368 includes a sibling node sourcename entry (e.g., sibling node DSN address) corresponding to where asibling node is stored in a DSN memory and/or a distributed storage andtask network (DSTN) module when the index node has the sibling node as asibling. The sibling node is another index node when the index node hasthe sibling. The sibling node source name field 368 may include a nullentry when the index node does not have a sibling. The sibling minimumindex key field 370 includes a sibling of minimum index keycorresponding to the sibling node when the index node has the siblingnode as the sibling. The sibling key type traits field 372 may includesibling key type traits corresponding to the sibling node when the indexnode has the sibling node as the sibling and when the sibling key typetraits field is utilized. Alternatively, index structure metadata mayinclude key type traits utilized globally for each node of the indexstructure.

The index structure metadata may include one or more of key type traitsto be utilized for all nodes of a corresponding index, key type traitsto be utilized for all index nodes of the corresponding index, key typetraits to be utilized for all leaf nodes of the corresponding index, asource name of a root node of the index structure, a maximum number ofindex structure levels, a minimum number of the next level structures, amaximum number of elements per index structure level, a minimum numberof elements per index structure level, and index revision number, and anindex name. The index structure metadata may be utilized for one or moreof accessing the index, generating the index, updating the index, savingthe index, deleting portions of the index, adding a portion to theindex, cloning a portion of the index, and searching through the index.The index structure metadata may be stored in one or more of a localmemory, one or more nodes of the index structure, and as encodedmetadata slices in at least one of the DSTN module and the DSN memory.

The child node source name field 378 includes a child node source nameentry (e.g., child node DSN address) corresponding to a storage locationfor the child node. For example, a child 1 node source name field 378 ofa child 1 node information section 374 includes a child 1 node sourcename. The child minimum index key field 380 includes a child minimumindex key corresponding to the child node. For example, a child 1minimum index key field 380 of the child 1 node information section 374includes a child 1 minimum index key. The child key type traits field382 may include child key type traits corresponding to the child nodewhen the index node has the child node as the child and when the childkey type traits field is utilized. Alternatively, the index structuremetadata may include key type traits utilized globally for each node ofthe index structure.

FIG. 11 is a diagram illustrating an example of a leaf node structure384 that includes leaf node information 388, sibling node information358, and data information 392. Alternatively, there is no sibling nodeinformation 358 when the leaf node has no sibling node. The leaf nodeinformation 388 includes one or more of a leaf node source name field394, a leaf node revision field 396, and a node type field 366.Inclusion and/or use of the leaf node source name field 394 and the leafnode revision field 396 is optional. The sibling node information 358includes a sibling node source name field 368, a sibling minimum indexkey field 370, and a sibling key type traits field 372. Inclusion and/oruse of the sibling key type traits field 372 is optional. The datainformation 392 includes one or more data information sections 398, 400,etc. corresponding to each data object associated with the leaf node.Alternatively, the data information 392 includes null information whenno data object is presently associated with the leaf node. Each datainformation section of the one or more data information sectionsincludes a corresponding data (e.g., data object) source name or datafield 402, a corresponding data index key field 404, and a correspondingdata key type traits field 406. For example, the corresponding datasource name field 402 of a data 1 node information section 398 includesa data 1 source name entry. Inclusion and/or use of the correspondingdata key type traits field 406 is optional.

The leaf node source name field 394 may include a leaf node source nameentry (e.g., leaf node distributed storage and task network (DSTN)address and/or a dispersed storage network (DSN) address) correspondingto a storage location of the leaf node. The leaf node revision field 396may include a leaf node revision entry corresponding to a revisionnumber of information contained in the leaf node. Use of the leaf noderevision enables generating two or more similar indexes while savingeach revision of the two or more similar indexes. The node type field366 includes a node type, where the node type indicates whether the nodeis a leaf node or not a leaf node. The node type indicates that the nodeis a leaf node when the node is the leaf node.

The sibling node source name field 368 includes a sibling node sourcename entry (e.g., sibling node DSN address) corresponding to a storagelocation for a sibling when the leaf node has the sibling node as asibling. The sibling node is another leaf node when the leaf node hasthe sibling. The sibling node source name field 368 may include a nullentry when the leaf node does not have a sibling. The sibling minimumindex key field 370 includes a minimum index key associated with thesibling node when the leaf node has the sibling node as the sibling. Thesibling key type traits field 372 may include sibling key type traitscorresponding to the sibling node when the leaf node has the siblingnode as the sibling and when the sibling key type traits field 372 isutilized. Alternatively, index structure metadata may include key typetraits utilized globally for each leaf node of the index structure.

The data source name or data field 402 includes at least one of a datasource name entry (e.g., a DSN address) corresponding to a storagelocation of data and the data (e.g., a data object, one or more encodeddata slices of data). For example, a data 1 source name or data field402 of a data 1 information section 398 includes a DSN address sourcename of a first data object. As another example, the data 1 source nameor data field 402 of the data 1 information section includes the data 1data object. The data index key field 404 includes a data index keycorresponding to the data. For example, a data 1 index key field orderfor of the data 1 information section 398 includes a data 1 index key.The data key type traits field 406 may include data key type traitscorresponding to the data when the data key type traits field 406 isutilized. Alternatively, the index structure metadata may include keytype traits utilized globally for each data object associated with theindex structure.

FIG. 12 is a schematic block diagram of an embodiment of engaging adelegate for updating a hierarchical index structure of a DSN. As shown,the DSN includes computing devices 12-16, the managing unit 18, theintegrity unit 20, at least two delegate devices 75 (or index updatemodules), and a storage set 85. The storage set includes a set of DSTexecution (EX) units 1-n or a set of storage units. Note that, each DSTexecution unit may be interchangeably referred to as a storage unit andthe storage set may be interchangeably referred to as a set of storageunits. Further note that the delegate device 75 may be implemented as aseparate computing device within the DSN or as part of another device ofthe DSN (e.g., computing devices 12-16, storage units 36, managing unit18, and/or integrity processing unit 20).

In an example of operation of the updating of the index node, acomputing device issues an update index node request 1 to the indexupdate module 1, where the update index node request includes at leastone of an add entry request and a delete entry request, and where theupdate index node request further includes one or more of a vaultidentifier (ID) (e.g., a universal unique identifier), an index ID, anentry identifier (e.g., an index key of the dispersed hierarchicalindex), and an entry. The issuing includes one or more of determining toupdate the index node, generating the update index node request 1,selecting the index update module 1, and sending, via the network 24,the update index node request 1 to the index update module 1. Theselecting includes at least one of interpreting system registryinformation, interpreting a query response, and identifying anassociation of the index ID and the index update module 1, etc.

When the update index node request is not associated with the indexupdate module 1, the index update module 1 forwards the update indexnode 1 request to another index update module that is associated withthe update index node 1 request. For example, the index update module 1indicates that the update index node request 1 is not associated withthe index update module 1 when a vault identifier and the indexidentifier are not associated with the index update module 1, identifiesthe index update module 2 as the other index update module based on thevault identifier and index ID (e.g., interpret system registryinformation), and sends, via the network 24, the update index noderequest 1 as a forwarded update index node request 1 to the index updatemodule 2.

Having received the forwarded update index node request 1, the indexupdate module 2 recovers the index node from the storage set. Forexample, the index update module 2 issues index slice requests 1-n,receives index slice responses, and dispersed storage error decodesreceived index slices A1-An to reproduce the index node. Havingrecovered the index node, the index update module 2 updates therecovered index node based on the received update index node request.For example, the index update module 2 modifies one or more entries ofthe recovered index node utilizing entries extracted from the forwardedupdate index node request 1 to produce an updated index node.

Having produced the updated index node, the index update module 2facilitate storage of the updated index node in the storage set. Forexample, the index update module 2 dispersed storage error encodes theupdated index node to produce an updated set of index slices A1-An, andsends, via the network 24, the updated set of index slices A1-An to theDST execution units 1-n for storage.

FIG. 13 is a logic diagram of an example of a method of engaging adelegate for a hierarchical index structure of a DSN. The methodincludes step 100 where a processing unit of a computing device, orother device of the DSN, issues an update index node request to a firstindex update module. For example, the processing unit determines toupdate the index node, generates the update index node request,identifies the first index update module (e.g., interpret systemregistry information, interpret a query response, interpret and indexkey responsibility list), and sends the updated index node request tothe first index update module.

When the update index node request is not associated with the firstindex update module, the method continues at step 112 where the firstindex update module forwards the update index node request to a secondindex update module. For example, the first index update moduleindicates that the update index node request is not associated with thefirst index update module when a vault identifier (ID) and/or an indexID is not associated with the first index update module, identifies thesecond index update module based on the vault ID and index ID (e.g.,interpret system registry information), and sends the update index noderequest to the second index update module. Alternatively, the firstindex update module processes the updated index node request.

The method continues at step 104 where the second index update modulerecovers a copy of the index node from the storage set. For example, thesecond index update module issues index slice requests to the storageset, receives index slice responses, and disperse storage error decodesreceived index slices to produce the copy of the index node.

The method continues at step 106 where the second index update moduleupdates the copy of the index node to produce an updated index nodebased on the update index node request. For example, the second indexupdate module modifies one or more entries of the recovered index nodeutilizing entries extracted from the received update index node request.

The method continues at step 108 where the second index update modulefacilitate storage of the updated index node in the storage set. Forexample, the second index update module dispersed storage error encodesthe updated index node to produce an updated set of index slices andsends the updated set of index slices to the storage set for storage.

FIG. 14 is a logic diagram of another example of a method of engaging adelegate for a hierarchical index structure of a DSN. The method beginsat step 110 where a computing device identifies a delegate device of aplurality of delegate devices of the DSN for processing a change to anode of a hierarchical index structure (e.g., a node of the indexstructure of FIG. 9). In an example, the computing device identifies thedelegate device by accessing a local copy of a list of delegate deviceresponsibilities. For instances, the list identifies a particulardelegate device and one or more nodes it has updating responsibilities.The list may further include, for the particular delegate device, whattype of changes to a node it can make (e.g., add, edit, delete, etc.).As such, when the computing device is access the list, it identifies theparticular delegate device based on the node, the type of change beingrequested, and/or the hierarchical index. Note that a DSN will typicallyhave multiple index structures for different topics and/orcategorizations of data (e.g., one for author's name, one for date, onefor alphabetic ordering, one for data type, etc.).

The method continues at step 112 where the computing device sends achange type specific request to the delegate device regarding a changeto the node. As an example, a first change type is to add an entry tothe node, is to add the node, and/or is to update an entry in the node.As another example, a second change type is to delete an entry to thenode and/or is to delete the node. As a specific example, when thechange is the first change type, the computing device generates an indexinsert request that includes a vault identifier, an index identifier,and an index entry. The index entry includes data regarding the changeto the node. The computing device then sends the index insert request tothe delegate device.

As another specific example, when the change is a second change type,the computing device generates an index remove request that includes avault identifier, an index identifier, and an index entry, wherein theindex entry includes data regarding the deletion to the node. Thecomputing device then sends the index remove request as the change typespecific request to the delegate device.

The method continues at step 114, where the delegate device determineswhether it is responsible for executing the change type specificrequest. For example, the delegate device accessing a local copy of alist of delegate device responsibilities regarding the plurality ofdelegate devices based on a type of change to the node, the hierarchicalindex, and on an identity of the node to determine responsibility. As analternative, the delegate device uses a deterministic function todetermine its index structure modification responsibilities. If thedelegate device is not responsible, the method continues as show in FIG.15, which will be subsequently discussed.

When the delegate device is responsible for executing the change typespecific request, the method continues at step 116 where the delegatedevice sends a response message to the computing device indicating thatit is responsible for executing the change type specific request. Themethod continues at step 118 where the delegate device executes thechange type specific request. For example, the delegate device retrievesa decode threshold number of encoded node slices from storage units ofthe DSN. Note that the node is dispersed storage error encoded toproduce the set of encoded node slices, which is stored in a set ofstorage units.

The example continues by recovering the node from the decode thresholdnumber of encoded node slices (e.g., decoding the encoded data slices).The example continues by modifying the node based on the change typespecific request to produce a modified node. When the node has not beendeleted, the example continues by dispersed storage error encoding themodified node to produce a set of updated encoded node slice. Theexample continues by sending the set of updated encoded node slice tothe set of storage units for storage therein.

FIG. 15 is a logic diagram of another example of a method of engaging adelegate for a hierarchical index structure of a DSN when the delegatedevice is not responsible. The method includes step 120 where thedelegate devices sends, to the computing device, a notice to update alist of delegate device responsibilities. The method continues at step122 where the delegate device determines whether it will process thechange type specific request, to not process the change type specificrequest, or to send the change type specific request to another delegatedevice.

If the delegate device determines not to process (NP) the request, itsends a response message to the computing device indicating that thedelegate device is not responsible for executing the change typespecific request. If the delegate device determines to process (P) therequest, the method continues at step 126 where the delegate devicesends a notice to the computing device indicating that it will processthe change type specific request. The method continues at step 128 wherethe delegate device executes the change type specific request to producean updated node.

When the delegate device determines to send the change type specificrequest to another delegate device (STA), the method continues at step130 where the delegate device sends a notice to the computing deviceindicating that it is sending the request to the other delegate device.The method continues at step 132 where the delegate device sends thechange type specific request to the other delegate device.

It is noted that terminologies as may be used herein such as bit stream,stream, signal sequence, etc. (or their equivalents) have been usedinterchangeably to describe digital information whose contentcorresponds to any of a number of desired types (e.g., data, video,speech, audio, etc. any of which may generally be referred to as‘data’).

As may be used herein, the terms “substantially” and “approximately”provides an industry-accepted tolerance for its corresponding termand/or relativity between items. Such an industry-accepted toleranceranges from less than one percent to fifty percent and corresponds to,but is not limited to, component values, integrated circuit processvariations, temperature variations, rise and fall times, and/or thermalnoise. Such relativity between items ranges from a difference of a fewpercent to magnitude differences. As may also be used herein, theterm(s) “configured to”, “operably coupled to”, “coupled to”, and/or“coupling” includes direct coupling between items and/or indirectcoupling between items via an intervening item (e.g., an item includes,but is not limited to, a component, an element, a circuit, and/or amodule) where, for an example of indirect coupling, the intervening itemdoes not modify the information of a signal but may adjust its currentlevel, voltage level, and/or power level. As may further be used herein,inferred coupling (i.e., where one element is coupled to another elementby inference) includes direct and indirect coupling between two items inthe same manner as “coupled to”. As may even further be used herein, theterm “configured to”, “operable to”, “coupled to”, or “operably coupledto” indicates that an item includes one or more of power connections,input(s), output(s), etc., to perform, when activated, one or more itscorresponding functions and may further include inferred coupling to oneor more other items. As may still further be used herein, the term“associated with”, includes direct and/or indirect coupling of separateitems and/or one item being embedded within another item.

As may be used herein, the term “compares favorably”, indicates that acomparison between two or more items, signals, etc., provides a desiredrelationship. For example, when the desired relationship is that signal1 has a greater magnitude than signal 2, a favorable comparison may beachieved when the magnitude of signal 1 is greater than that of signal 2or when the magnitude of signal 2 is less than that of signal 1. As maybe used herein, the term “compares unfavorably”, indicates that acomparison between two or more items, signals, etc., fails to providethe desired relationship.

As may also be used herein, the terms “processing module”, “processingcircuit”, “processor”, and/or “processing unit” may be a singleprocessing device or a plurality of processing devices. Such aprocessing device may be a microprocessor, micro-controller, digitalsignal processor, microcomputer, central processing unit, fieldprogrammable gate array, programmable logic device, state machine, logiccircuitry, analog circuitry, digital circuitry, and/or any device thatmanipulates signals (analog and/or digital) based on hard coding of thecircuitry and/or operational instructions. The processing module,module, processing circuit, and/or processing unit may be, or furtherinclude, memory and/or an integrated memory element, which may be asingle memory device, a plurality of memory devices, and/or embeddedcircuitry of another processing module, module, processing circuit,and/or processing unit. Such a memory device may be a read-only memory,random access memory, volatile memory, non-volatile memory, staticmemory, dynamic memory, flash memory, cache memory, and/or any devicethat stores digital information. Note that if the processing module,module, processing circuit, and/or processing unit includes more thanone processing device, the processing devices may be centrally located(e.g., directly coupled together via a wired and/or wireless busstructure) or may be distributedly located (e.g., cloud computing viaindirect coupling via a local area network and/or a wide area network).Further note that if the processing module, module, processing circuit,and/or processing unit implements one or more of its functions via astate machine, analog circuitry, digital circuitry, and/or logiccircuitry, the memory and/or memory element storing the correspondingoperational instructions may be embedded within, or external to, thecircuitry comprising the state machine, analog circuitry, digitalcircuitry, and/or logic circuitry. Still further note that, the memoryelement may store, and the processing module, module, processingcircuit, and/or processing unit executes, hard coded and/or operationalinstructions corresponding to at least some of the steps and/orfunctions illustrated in one or more of the Figures. Such a memorydevice or memory element can be included in an article of manufacture.

One or more embodiments have been described above with the aid of methodsteps illustrating the performance of specified functions andrelationships thereof. The boundaries and sequence of these functionalbuilding blocks and method steps have been arbitrarily defined hereinfor convenience of description. Alternate boundaries and sequences canbe defined so long as the specified functions and relationships areappropriately performed. Any such alternate boundaries or sequences arethus within the scope and spirit of the claims. Further, the boundariesof these functional building blocks have been arbitrarily defined forconvenience of description. Alternate boundaries could be defined aslong as the certain significant functions are appropriately performed.Similarly, flow diagram blocks may also have been arbitrarily definedherein to illustrate certain significant functionality.

To the extent used, the flow diagram block boundaries and sequence couldhave been defined otherwise and still perform the certain significantfunctionality. Such alternate definitions of both functional buildingblocks and flow diagram blocks and sequences are thus within the scopeand spirit of the claims. One of average skill in the art will alsorecognize that the functional building blocks, and other illustrativeblocks, modules and components herein, can be implemented as illustratedor by discrete components, application specific integrated circuits,processors executing appropriate software and the like or anycombination thereof.

In addition, a flow diagram may include a “start” and/or “continue”indication. The “start” and “continue” indications reflect that thesteps presented can optionally be incorporated in or otherwise used inconjunction with other routines. In this context, “start” indicates thebeginning of the first step presented and may be preceded by otheractivities not specifically shown. Further, the “continue” indicationreflects that the steps presented may be performed multiple times and/ormay be succeeded by other activities not specifically shown. Further,while a flow diagram indicates a particular ordering of steps, otherorderings are likewise possible provided that the principles ofcausality are maintained.

The one or more embodiments are used herein to illustrate one or moreaspects, one or more features, one or more concepts, and/or one or moreexamples. A physical embodiment of an apparatus, an article ofmanufacture, a machine, and/or of a process may include one or more ofthe aspects, features, concepts, examples, etc. described with referenceto one or more of the embodiments discussed herein. Further, from figureto figure, the embodiments may incorporate the same or similarly namedfunctions, steps, modules, etc. that may use the same or differentreference numbers and, as such, the functions, steps, modules, etc. maybe the same or similar functions, steps, modules, etc. or differentones.

Unless specifically stated to the contra, signals to, from, and/orbetween elements in a figure of any of the figures presented herein maybe analog or digital, continuous time or discrete time, and single-endedor differential. For instance, if a signal path is shown as asingle-ended path, it also represents a differential signal path.Similarly, if a signal path is shown as a differential path, it alsorepresents a single-ended signal path. While one or more particulararchitectures are described herein, other architectures can likewise beimplemented that use one or more data buses not expressly shown, directconnectivity between elements, and/or indirect coupling between otherelements as recognized by one of average skill in the art.

The term “module” is used in the description of one or more of theembodiments. A module implements one or more functions via a device suchas a processor or other processing device or other hardware that mayinclude or operate in association with a memory that stores operationalinstructions. A module may operate independently and/or in conjunctionwith software and/or firmware. As also used herein, a module may containone or more sub-modules, each of which may be one or more modules.

As may further be used herein, a computer readable memory includes oneor more memory elements. A memory element may be a separate memorydevice, multiple memory devices, or a set of memory locations within amemory device. Such a memory device may be a read-only memory, randomaccess memory, volatile memory, non-volatile memory, static memory,dynamic memory, flash memory, cache memory, and/or any device thatstores digital information. The memory device may be in a form a solidstate memory, a hard drive memory, cloud memory, thumb drive, servermemory, computing device memory, and/or other physical medium forstoring digital information.

While particular combinations of various functions and features of theone or more embodiments have been expressly described herein, othercombinations of these features and functions are likewise possible. Thepresent disclosure is not limited by the particular examples disclosedherein and expressly incorporates these other combinations.

What is claimed is:
 1. A method comprises: identifying, by a computingdevice of a dispersed storage network (DSN), a delegate device of aplurality of delegate devices of the DSN for processing a change to anode of a plurality of nodes of a hierarchical index structure, whereinthe hierarchical index structure is used to identify particular datastored in the DSN and wherein the plurality of nodes includes a rootindex node, a plurality of plurality of index nodes, and a plurality ofleaf index nodes arranged in a related hierarchical manner; sending, bythe computing device, a change type specific request to the delegatedevice regarding the change to the node; determining, by the delegatedevice, whether the delegate device is responsible for executing thechange type specific request; when the delegate device is responsiblefor executing the change type specific request: sending, by the delegatedevice, a response message to the computing device indicating that thedelegate device is responsible for executing the change type specificrequest; and executing, by the delegate device, the change type specificrequest.
 2. The method of claim 1, wherein the identifying the delegatedevice comprises: accessing a local copy of a list of delegate deviceresponsibilities regarding the plurality of delegate devices based on atype of change to the node, the hierarchical index structure, and on anidentity of the node to identify the delegate device.
 3. The method ofclaim 2 further comprises: when the delegate device is not responsiblefor executing the change type specific request: sending, by the delegatedevice, a response message to the computing device indicating that thedelegate device is not responsible for executing the change typespecific request; and updating, by the computing device, the list toinclude that the delegate device is not responsible for executing thechange type specific request.
 4. The method of claim 1, wherein thesending the change type specific request comprises: when the change to anode is to add an entry to the node, is to add the node, or is to updatean entry in the node: generating, by the computing device, an indexinsert request that includes a vault identifier, an index identifier,and an index entry, wherein the index entry includes data regarding thechange to the node; and sending, by the computing device, the indexinsert request as the change type specific request.
 5. The method ofclaim 1, wherein the sending the change type specific request comprises:when the change to a node is to delete an entry to the node or is todelete the node: generating, by the computing device, an index removerequest that includes a vault identifier, an index identifier, and anindex entry, wherein the index entry includes data regarding the changeto the node; and sending, by the computing device, the index removerequest as the change type specific request.
 6. The method of claim 1further comprises: when the delegate device is not responsible forexecuting the change type specific request: sending, by the delegatedevice, a notice to update a list of delegate device responsibilities tothe computing device; determining, by the delegate device, whether toprocess the change type specific request, to not process the change typespecific request, or to send the change type specific request to anotherdelegate device of the plurality of delegate devices; when the delegatedevice determines to process the change type specific request: sending,by the delegate device, a notice to the computing device regardingprocessing the change type specific request; and executing, by thedelegate device, the change type specific request to produce an updatednode.
 7. The method of claim 6 further comprises: when the delegatedevice determines to send the change type specific request to anotherdelegate device of the plurality of delegate devices; sending, by thedelegate device, a notice to the computing device regarding the sendingto the other delegate device; and sending, by the delegate device, thechange type specific request to the other delegate device.
 8. The methodof claim 1, wherein the determining whether the delegate device isresponsible for executing the change type specific request comprises:accessing a local copy of a list of delegate device responsibilitiesregarding the plurality of delegate devices based on a type of change tothe node, the hierarchical index structure, and on an identity of thenode to determine responsibility.
 9. The method of claim 1, wherein theexecuting the change type specific request comprises: retrieving adecode threshold number of encoded node slices from storage units of theDSN, wherein the node is dispersed storage error encoded to produce aset of encoded node slices, wherein the set of encoded node slices isstored in a set of storage units, and wherein the decode thresholdnumber of encoded node slices represents a minimum number of encodednode slices of the set of encoded node slices needed to recover thenode; recovering the node from the decode threshold number of encodednode slices; modifying the node based on the change type specificrequest to produce a modified node; when the node has not been deleted,dispersed storage error encoding the modified node to produce a set ofupdated encoded node slice; and sending the set of updated encoded nodeslice to the set of storage units for storage therein.
 10. A computerreadable memory comprises: a first memory element that storesoperational instructions that, when executed by a computing device of adispersed storage network (DSN), causes the computing device to:identify a delegate device of a plurality of delegate devices of the DSNfor processing a change to a node of a plurality of nodes of ahierarchical index structure, wherein the hierarchical index structureis used to identify particular data stored in the DSN and wherein theplurality of nodes includes a root index node, a plurality of pluralityof index nodes, and a plurality of leaf index nodes arranged in arelated hierarchical manner; and send a change type specific request tothe delegate device regarding the change to the node; a second memoryelement that stores operational instructions that, when executed by thedelegate device, causes the delegate device to: determine whether thedelegate device is responsible for executing the change type specificrequest; when the delegate device is responsible for executing thechange type specific request: send a response message to the computingdevice indicating that the delegate device is responsible for executingthe change type specific request; and execute the change type specificrequest.
 11. The computer readable memory of claim 10, wherein the firstmemory element further stores operational instructions that, whenexecuted by the computing device, causes the computing device toidentify the delegate device by: accessing a local copy of a list ofdelegate device responsibilities regarding the plurality of delegatedevices based on a type of change to the node, the hierarchical indexstructure, and on an identity of the node to identify the delegatedevice.
 12. The computer readable memory of claim 11 further comprises:the second memory element further stores operational instructions that,when executed by the delegate device, causes the delegate device to:when the delegate device is not responsible for executing the changetype specific request: send a response message to the computing deviceindicating that the delegate device is not responsible for executing thechange type specific request; and the first memory element furtherstores operational instructions that, when executed by the computingdevice, causes the computing device to: update the list to include thatthe delegate device is not responsible for executing the change typespecific request.
 13. The computer readable memory of claim 10, whereinthe first memory element further stores operational instructions that,when executed by the computing device, causes the computing device tosend the change type specific request by: when the change to a node isto add an entry to the node, is to add the node, or to update an entryin the node: generate an index insert request that includes a vaultidentifier, an index identifier, and an index entry, wherein the indexentry includes data regarding the change to the node; and send the indexinsert request as the change type specific request.
 14. The computerreadable memory of claim 10, wherein the first memory element furtherstores operational instructions that, when executed by the computingdevice, causes the computing device to send the change type specificrequest by: when the change to a node is to delete an entry to the nodeor is to delete the node: generate an index remove request that includesa vault identifier, an index identifier, and an index entry, wherein theindex entry includes data regarding the change to the node; and send theindex remove request as the change type specific request.
 15. Thecomputer readable memory of claim 10, wherein the second memory elementfurther stores operational instructions that, when executed by thedelegate device, causes the delegate device to: when the delegate deviceis not responsible for executing the change type specific request: senda notice to update a list of delegate device responsibilities to thecomputing device; determine whether to process the change type specificrequest, to not process the change type specific request, or to send thechange type specific request to another delegate device of the pluralityof delegate devices; when the delegate device determines to process thechange type specific request: send a notice to the computing deviceregarding processing the change type specific request; and execute thechange type specific request to produce an updated node.
 16. Thecomputer readable memory of claim 15, wherein the second memory elementfurther stores operational instructions that, when executed by thedelegate device, causes the delegate device to: when the delegate devicedetermines to send the change type specific request to another delegatedevice of the plurality of delegate devices; send a notice to thecomputing device regarding the sending to the other delegate device; andsend the change type specific request to the other delegate device. 17.The computer readable memory of claim 10, wherein the second memoryelement further stores operational instructions that, when executed bythe delegate device, causes the delegate device to determine whether thedelegate device is responsible for executing the change type specificrequest by: accessing a local copy of a list of delegate deviceresponsibilities regarding the plurality of delegate devices based on atype of change to the node, the hierarchical index structure, and on anidentity of the node to determine responsibility.
 18. The computerreadable memory of claim 10, wherein the second memory element furtherstores operational instructions that, when executed by the delegatedevice, causes the delegate device to execute the change type specificrequest by: retrieving a decode threshold number of encoded node slicesfrom storage units of the DSN, wherein the node is dispersed storageerror encoded to produce a set of encoded node slices, wherein the setof encoded node slices is stored in a set of storage units, and whereinthe decode threshold number of encoded node slices represents a minimumnumber of encoded node slices of the set of encoded node slices neededto recover the node; recovering the node from the decode thresholdnumber of encoded node slices; modifying the node based on the changetype specific request to produce a modified node; when the node has notbeen deleted, dispersed storage error encoding the modified node toproduce a set of updated encoded node slice; and sending the set ofupdated encoded node slice to the set of storage units for storagetherein.